Luckily, you can't be reinfected by the same cold virus, but there are some 200 different strains circulating at any given time.

“You develop antibodies for each of the viruses you are exposed to,” said Dr. Natalie Azar, NBC medical contributor. “If you are having a cold that feels like it just doesn’t quit, it is probably a different cold virus.”

Charles Gerba, a professor of microbiology and environmental sciences at the University of Arizona, agreed.

Yuck factor

On the other side, Gerba says not to worry too much about toothbrushes spreading illness.

“It is just a yuck factor,” he said.

However, it is generally recommended to change your toothbrush every three months. And keep it away from the toilet, because airborne droplets released from flushing settle on toothbrushes, Gerba advised.

And, never share toothbrushes.

“You can catch infections like a cold, bloodborne disease [think Hepatitis B or C], or even bacterial infections if you take a chance and use someone else’s toothbrush,” Rosen said.

It's not about you

When it comes spreading colds and influenza, bar soap and towels can be germ factories. After rubbing hands on the soap, the germs remain on the bar, said Gerba. If people fail to sufficiently wash the germs off their hands, the leftovers may cling to hand towels.

“They can be a conduit for transmitting germs,” said Gerba. “Change those towels every two or three days.”

Sheets can also harbor germs, which could infect a healthy bed partner if they remain unwashed after illness.

“Viruses can survive much, much shorter periods of time on a porous surface,” says Azar. But they can linger up to 24 hours on hard surfaces, such as counters, tables, computer keyboards, and remote controls.

It doesn't take much to clean away most germs, fortunately. Azar suggests thoroughly cleaning the house, sheets and towels after illness “if you want to be kind to other people. It’s not about you — it is about other people.”